Electrical insulation testing apparatus



April 27,1948. C. LEWIS 2,440,480

ELECTRICAL INSULATION TESTING APPARATUS Filed March 31 1944 PatentedApr. 27, 1948 2.4404801? ELECTRICAL INSULATION TESTING,

, APPARATUS Clay E. Lewis, Baltimore, Md.,'assignor to Western ElectricCompany, Incorporated, New York, 1 N. Y., a corporation of New York IApplication March 31, 1944, Serial No. 528,823

' 8 Claims. (015175 183) This invention relates to testing apparatus andmore particularly to apparatus for testing the insulation of electricalconductors.

It is necessary to test the insulation of some types of electricalconductors for minimum periods of time. In such testing operations withtesting'apparatus heretofore known, it has been necessary for anoperator thereof to time the period of each test by ordinarychronological means and thus the attention of the operator is divertedfrom other duties required in the testing operations. In addition, therewas a tendency for the operator to shorten the testing periods below theminimum periods required.v

An object of the invention is to provide new and improved testingapparatus.

One device embodying the invention comprises a testing circuit and meansfor controlling the operation of the circuit, including a startingswitch, a timing unit having a synchronous motor drive with a high speedreset-to-zero mechanism associated therewith and also having a pluralityof contacts opened thereby at predetermined difierent intervals, and aplurality of relays associated with the timer and the starting switchandv which operate in such sequence that, when the starting switch isactuated, the timer is started and the testing circuit is energized, therelays and timers being so designed that, after the timer has beenplaced into operation, it continues to operate for a predeterminedperiod regardless of whether the starting switch is closed.

A complete understanding of the invention may be obtained from thefollowing detailed-description of a specific embodiment thereof, whenread.

in conjunction with the appended drawings, in which Fig. 1 illustratesschematically a portion of a device embodying the invention;

Fig. 2 is a vertical, sectional view of a portion of the device takenalong line 2-2 of Fig. 1;

Fig. 3 is a sectional view of a portion of the device taken along line3-3 of Fig.1; a

Fig. 4 is a vertical, sectional view of a portion of the device takenalong line 4-4 of Fig. 1, and Fig. 5 is a vertical, sectional'viewof aportion of the device taken along line 5-5 ofFig. 1.

Referring to the drawings, a conductor l (Fig. 1) leading from aconductor ll of a power line 52 connects a sensitive coil l of arelay-|=6 to the conductor A contactor l6 serves to bridge contacts|9-|9 of theconductor A second coil 26 of the relay [6, is connected toa conductor 2| oi the power; line I2 by a conductor 22 having a norm llopen,

I! of the relay manually operated switch 23 therein. A conductor 25connects the conductor to the coil 20.; r

A conductor 26 (Fig. 1) connects the other side ofthel'coil 15 to acontact 21 of a relay 29. The 5 relay 29 includes contactors 30 and 3|which, when closed, are adapted to bridge the contact -21 and a contact32 and contacts 33- -33, respectively, to'supply power to a-primary;winding 35 of a step-up transformer 36. Arconductor His 110 connected toone of the contacts 33 and to the conductor 2|. w a 1 The transformer 36(Fig 1) includes a secondary winding 39 which is also includedin atesting circuit 46. The testingcircuit 40 includes 15 a resistance 4|connected to a conductor 42, which has an insulating cover43 thereon,iofa cable 45 to be tested and a grounded conductor -45, which isconnectedto a second conductor and a ,metallic braid 48 of thecable '45. A con-20 ductor 49 gro unds one side or the secondary winding 99. l I v a Arelay 5!) (Fig. 1) is supplied power iromithe conductor through aconductor 5| andirom the conductor 2| through aconductor 52 whichzsrincludes a manually operated switch 55 which is open when the deviceis not in operation. When the switch- 55 is closed the relay56 .isenergized to force contactors 56 and 51 thereof into bridging engagementwith contacts 59 and 6d, and 6| 30 and 62, respectively. The contact 59is connected to a timer by a conductor 66 and the contact 66 isconnected to theconductor 2| by a conductor 61. Thecontact .62 isconnected to the conductor 5| by a conductor 69.

The contact 6| (Fig. 1) is connected to a conductor 10 which isconnected we contact ll of ya relay 12. The coil of the relay 12 isconnected to the conductor 2| by a conductor 15 and .to the timer 65 bya conductor 16. A contact 'llof the 40 relay I2 is connected to theconductor 16by a conductorfw. The relay 12 also includes contacts 8 0and 8| andthecontact is connected fto-the conductor 52 while the contact8| is conn ectedto the coilof the relay 29 by a conductor 62. When therelay 12 is energized, contactors .85 ,and 86 thereof bridge the,contacts "and 11, and 80 and 8| respectively, to energize the coil orthe relay 29, which is connectedto the conductor H by a conductor 88,and an indicat- 50, ing lamp 8'! connected in parallel withthe coil oftherelay 29. v

;The winding of a motor 96 (Fig. 1) of the timer 65 ,is connected to theconductor I by a conductor 91 and to a contact 99 of a relay )6 by 5 aconductorilfll; and the winding ofan electro- "'ductor' I 30 whenthee-contact ductorfic. The connection magnet I02 is connected to theconductors 91 and ItlI by conductors 15-405. When in operation, themotor 96 rotates a gear I06 which rotates a gear I01 and thereby rotatesa pair of intermeshed gears I09 and III]. Thus, a shaft 5 III in whichthe gear H is secured and which is slidably *mountledain hearings itITimid I I3; is rotated. I

An armature II (Fig. 1) of the electromagnet 4 starting position, asshown in Fig. 4, forces a contactor I45 into engagement with the contactI31. After the cam I28 has been rotated in a clockwise direction so thata dwell I46 thereof engages the contact I45, the engagement between thecontactor I45 and the contact I31 will be -brolgenybut it isuonlyatrthat time that. the engagementitherebetwee is ibroken. The contactorI45 is connected to the conductor II by a con- I02 is pivotally mountedon an arm IIB of theitlmductor I41 (Fig. 1) with an indicating lamp I48electromagnet and is pivoted in. aecountercflockwise direction, as seenin Fig. I, whemthe-iciifl of the electromagnet I02 is energized, thusurging the shaft III to the rightagainststheeaction of a, coil spring IIII] and the hearing '3. A driving clutch disc I I8 secured to the shaftIII issmovednthenebydnto engagement with a driven clutch disc II9secured to a shaft I2I1- rotatably mounted in bearings I2I-I2I. Whenmheelectromagnet I02 is 'deenergized; the spring l I; I1 moves the:chitchtdisc I I 8 -out of engagement wv'ith the 1 clutchadisd 'I I 9andaretum sprmg l'lzllliigs. lirand'ifmiof a conventional type serves tourg'ethel siiafti tZIkback to its original starting position. "The:inner :end of-the return 'spring -I22E(:Fig.="5) is'a-securedwtotheshaft "I20 and 'the outer renda't'hereoiais securedto afiXed9l'rn'ziifinie f2'3i' Thu's ,aid0g .IZlvsecuredto'the shaft I21! isurged :into :engagement with a-"stop -125*- wheri the clutch discsztlaamdtso II9 are out of engagement, and, whenrtheiishaft I20 isat'rest; it will-beheld=intha positionrshown -i1i1ifig; 5. y

'43 are"adjustably secured-to the shaft" iI 2II. A385 'lcontactor "F29connected-* to -"the conductor 'lll by a'conductoF'I W-hears against 'aslob l fl fifig'l 2) "of the'carn'il 26'; andtne Iobe I SI-forces'thecontactor I2 9 into *engagementmWh a: contact 132 andaccontactorelfifi thereof against nseries therewith. 'ifIZhe' coilof'the relay to the conductor II and I8 9 (Fi 1) is connected the contactorI by conrespectively. When the ielay l flll is energized, it forces acontactor I54 thereof against the'contact MI and a contact I59 v acontact I60 and the contact 99. The contacts I59 and I60 are connectedby a conductor I6I and a conductor I62 connects the contact I60 to theconducetorr2l.

.azlni'themperationrof the*device-described hereinabove, the cabledltijis-placed in the testing cirzcuitfl 0;. ashescrihhd hereinabove; and.the switch -55) is ciosedgrntzthistime, the cams-{26,1 I21v and t2 &'areizinrthe position: shown :in the drawings, .:that-is;:-;1in:theiit;s.tarting positions. 1' After the 'i-switch i5 5'; isclosed',rthe :reiayr. is energized and Jana-contacts Stand r62 rare:bridged byv thereonatactor 5 'lzandz-theczcontacts 45,9 iandiBI] e arebridged ia-by the-acontactorvfifi. When rthercontactor :51 zhridges:thewcontactsr6 Ierand v:Ii2gigthe conductor rfi9tis aconnectedzito theconductors 10. and-I30 to energizatthe'crelay- 12rth-rough a: circuitincluding ':the conductor 15,:1thez160i1 of the relay 412-, theconductor I6, thescontact I:32, -the,contactorI-29, zzthexcnnductor. 3130, ethezrconductor 1.10, the conrtact'sfi I',E:the:contactor :S'htthe,eontact :62; and the :conductors remand: 15 I. The energized :re'lay:12

'whenthe niotor*96- is deen'erg-i'z'ed and *the 'shaftw lo:3then:forcesthezcontactor:8-6 into engagementwith I20 is in itsstarting position, as shown in the "drawings. The' con'tact W 32isconnecfied-"to'hthe iconduct0r 16 andthus' the conductor ise'lectricaily .connected'to the conductor '1-u-by the conm -and the een'45 :tactor I29: *are inrengagement. Whenthe ==cam I26= is rotated in'aclockwi'se direction; 'as ishown .ifiif'Fig; 2;theiob I'3I'? is-mevedpast the -contac- .torl29 'tb breakthe connction hetwe'en'theconitactofflSfahdthe'wHtact connection betweerrtheconductorwandtheconbetween-the-contact I32 and the "contactor I2 9' i'sbroken at all times except when the"contactor'-I-2 9iis in=engagementrorce a'contactor "F35. -into engagementwith a,

contact I3 5;";When the c'amil-fl'has been rotated clockwise asshowrtin.Wh'ich adw'elI "(IMbfthg cam I21 engages the contactor; I35""the'engagement between the confactor. [35 and; .the z'co'ntaet W3515 --broken. EX- cept. IWhEI'I .in engagement Withfithe "dwell Hfifofthe cam? r2 1,-tneicontactor "r35 'i'sftorc'ed =by'the" P zull-uminationof thelamp'81 will indicate that the periphery "I33 "'oflthe 'eam r21into enga ement 7 w h; theicontact I136. j

Theeontacmse is tconnectedto a'contacfi I31 ..T(1ji'g. .1) V .by, aconductor 1'39 "and the-conductor 1393.116 the contact"I31"areconne'ctedto-tne eon-- --7 tact 59.,by the conductor 66. The-contact I31 theconductors "139' and BRard-conne'c-ted to -thercontacts-89andi8 hand the:contactor 85 into iengagementvwithsthe; contacts 1 Ir and 11. When the:contactorzfifirbridgesitheizcontacts 1 I and 11, thesrelayfl 2. isrenergize d .byithet'conductors'i 5 ;;t11e :jzconductors i16..and219;1the.. contact 11;:the .con- ;-.tactor. :18 5;:the I contact :1I, -;:the: conductor :19: -the contact '56 I&,:*.the contactor I51,the-contact 62: and

:the conductors: 69-and 5|.

. fwhenithe lcontaotor 8fi:bridges";thexcontacts'tfl and i8 I';:-.the"coil ofrzthe relayzais energized to I =forcei-the rcontactors 30; and :3I :against' the con- .;.tacts 21 and132 ;andi33-r-433, respectively;where- ='.by-the primary :windingx35 Iof .the transformer 36 a isenergized; which: fact: isaindicated by. the .-illu- ;ing :cover'flfi ontheweonductori-42 is-not def ective,

.minatiorr ofpthe lamp 281.: :I-Iowever; if the insulatthere will bevery little current passing through ::the circuit 40,zanduthereforeverylittle current passing through thecircuitincluding'the primary winding 35 of thetransformerrfli and thesensitive "coi1 i I5 :of the relay l 6, and the coil I 5 will snot:"beenergized:sufficiently to 'force the contactor I1 oithe' relay I6 awayfrom the contacts?I9 I9." The contactor fl willthen remaininiengagement-with 'the contacts I-9-I9 and the insulating-coveri 43'ofrthe conductor 42 has not eye't beenf'o'und faultyand that the testis being continued.

Assuming that theinsulating cover 43 of the -:conductor 42 is notiaulty;when the contactor 56 is -forced into engagement with the contacts 59;-and -IiII, --as described hereinabove, the lamp I M H g g r 448--isilluminated -to 'indicate the operation of Aperipheiy 1 4%: the mamizemwhen in its the timer fiaand a circuit is *completedfrom theconductor u through the conductor 150, the coil of the relay I00, theconductor I 5I, the contactor I35, which is pressed by the periphery I33of the cam I21 against the contact I 36, the contact I36. the conductorsI39 and-66, thecontact 59, the contactor 56, the contact 60 and theconductor 61 to the conductor 2I, whereby the relay I is energized. Theenergization of the relay I00 forces the contactor I55into engagementwith the contacts 99 and I60, andthe contactor I54 into engagement withthe contacts MI and I59. When the contactor I55 bridges the contacts 99and I60, the relay I 00 receives power from the conductor 2I through theconductors I62 and I6I, the contact I59, the contactor I54, the contactI4I, the conductors I43 and I39, contact I36, contactor I35, and theconductor I5I, and from the conductor II through the conductor I50.Thus, the contactors I 54 and I55 will be retained in engagement withtheir respective contacts as long as the engagement between thecontactor I35 and the contact I36 is maintained, even if the relay'50should be deenergized by the opening of the switch 55.

When the contactor I55 of the relay I00 bridges the contacts 99 and I60, a circuit is completed from the power line I2 through the conductorsII and 91, the motor 96, the conductor IOI, the contact 99, thecontactor I55, the contact I60, and the conductors I62 and 2I, thusstarting the motor 96. The motor 96 drives the gear H0 at a uniform,slow rate of speed through the gears I06, I01 and I09 to rotate theshaft I II and the clutch disc II8 secured thereto. Simultaneously,

the electromagnet I02 is energized, thereby forcing the shaft I II tothe right, as viewed in Fig. 1, to force the driving clutch disc II8into engagement with the driven clutch disc H9 and the shaft I20 and thecams I26, I21 and I28 secured thereto are thereby rotated in clockwisedirections, as viewed in Figs. 2, 3 and 4, against the action of thereturn spring I 22. The speed of the motor 96 and the ratios of thegears I06, I 01, I09 and H0 are such that the shaft I20 is rotatedthrough the major portion of a circle in a period of time slightly overone minute. This period of time is slightly greater than the minimumperiod of time through which the insulating cover 43 should be tested,which period of time is approximately one minute. If they lamp 81remains lighted, indicating that only a, small current is passingthrough the testing circuit 40, the switch 55 should be kept closed bythe operator to continue the test, and if it is kept closed, the lamp 81remains illuminated to indicate that fact.

When the lobe I3I (Fig. 2) of the cam I26 is rotated past the contactorI 29 a few seconds after the start of the testing operation initiated bythe closing of the switch 55 (Fig; 1), the'engagement between thecontactor I29 and the contact I32' is broken. However, the breaking ofthe engagement between'the contactor I29 and the contact I32 does notdeenergize the relay 12 if the switch 55 is closed, because the circuitfrom the power line I2 through the conductors 2| and 15, the coil of therelay 12, the conductors '16 and 19, the contact 11, the contactor 85,the contact H, the conductor 10, the contact 6|, the contactor 51, thecontact 62, and the conductors 69, 5| and II remains closed as long asthe switch 55-is not opened by the operator. However, if, at any timethereafter during the test period, the switch 55 is opened, the relay 50is deenergized, which deenergizes the relay 12, and the relay 12 cannotbe energized again until after the timer 65 finishes its cycle andreturns to the starting position when the lobe I3 I again forcesthe'contactor I 29 against the contactI32.

Meanwhile, if the insulating cover on the conductor 42 is free fromdefects, the shaft I20 continues to be rotated in a clockwise direction,as shown in Fig. 2. Approximately one minute after the switch 55 isclosed, the dwell I46 (Fig. 4) of the cam I28 is moved into engagementwith thecontactor I 45, the engagement between the contactor I45 and thecontact I31 is broken and the lamp I48 goes out, thereby indicating thetranspiration of the minimumtest period. The operator then opens theswitch 55. However, the contactor I35 is still held by the periphery I33of the cam I21 (Fig. 3) in engagement with the contact I36, therebycausing the motor 96 and the electromagnet I02 to remain in operationfor a few seconds longer, until the dwell I34 of the cam I21 is rotatedto a position in engagement with the contactor I35 and the connectionbetween the contactor I35 and the contact I 36 is broken thereby. Thedisengagement of the contactor I35 and the contact I36 deenergizes therelay I00, thereby opening the connections between the contactors- I 54and I55 and the contacts MI and I 59, and 99 and I60, respectively,whereby the motor 96 and theelectromagnet I02 are deenergized. Upon thedeenergization of the electromagnet I02 the spring II1 moves the clutchdisc II8 away from the clutch disc I I9 and the return spring I22rotates the shaft I20, the cams I26, I21 and I28, and the dog I24, backto their starting positions, after which a testing operation upon aninsulating cover of another conductor similar to the conductor 42 may beconducted. The resetting operation just described occurs quickly and,because of this fact, the resetting operation does not start until ampletime after the lamp I40 goes out for the switch 55 to be opened prior tothe return to the starting position.

If the switch 55 is maintained closed for the minimum test period, whichis indicated by the illumination of the lamp I48, the lamp 81 willremain illuminated during that period. However, if the switch 55 isopened prior to the time that the lamp I48 goes out, the lamp '31 willgo out, which, together with the illumination of the lamp I48, willindicate that the test of the conductor 19 is not being conducted therequired time. The light I 48 will remain illuminated for the minimumtest period because the relay I 00 will remain energized by the circuitthrough the conductors 2|, I62 and I6I, the contact I59, the contactorI54. the contact I4I, the conductors I43 and I39, the contact I 36, thecontactor I35, the conductor I5I, the coil of the relay I00, and theconductors] I and I50, even though the switch 55 has been opened priorto the expiration of the minimum-test period. Thus, the contactor I55will be retained in engagement with the contacts 99and I60 and thecircuit to the motor 96 and the electromagnet I02 will remain closed.Consequently. the cams I26,- I21 and I28 will continue to rotate eventhough the switch 55 is prematurely opened. But, if the switch 55 isopened prematurely after the lobe I3I has moved out of engagement withthe contactor I29, reclosing of the switch 55 will not energizethe-relay 12 and another testing operation cannot be starteduntil thetimer 65 has returned to the starting position.

If the insulatingcover 43 (Fig. 1) is not indicated to be fault but theswitch 55 is opened before the lamp I48 goes' out, this failureto testling the continuity ofthe energizing means, manually controlledmeansforenergizing the conti- 7 :thec conductor -42 :lthe {required aperiodof time .mawzbe-iobserued: -eas ily-; -by, a supervisor, since the lampI48 is still illuminated ;*but;the-, lamp -83; iaonote Also, thelabovedescribed :device :re-

dniceszanyiincentive; to" shortenthe: periodof, ac- '5 ztnalgzthsting,sinceianotheritesting; operatiomcannot she: started; after a shortenedoperationuntil 'thQT CQHtaC'fiOI's 1:29 isiorced into engagementxwith:the contact i312 when. the-cam F26 is-returned :to;itststartingrpositionpby the return spring l 22, :10

asadesnrzibed hereinabove.

iilfntherdis. a xfiaultinothevinsulation-of the zconductorz 162 ,1.therreSistance: of 1 the I circuit All zwillzbeilowsienoughithat ahighcurrent will pass :therethrough; thusvcausing a: greater flowofourrentsthrough the-primary winding 35 of the trans- :iormer 3t.;'1"his surgesoi current-through the :primary. winding 35. r and thecoil 5 will: enerl-gizeitheg coil? .l 5;1sufficien tly to -force thecontactor :i-lrofixthezrelay: lB'aWay from the contacts 4-9-4 9 (.420

aandntheneby; :deenergize the entire-device. Thus, 'therlamps"8:l :and':M8 willpg-o out simultaneously to indicate a defect; in. thezinsulatingcover 4-3. If therdevic'ez isnsordeenergized, the. timerv 55 will returntositswstartingeposition. The conductor, 42= may then she:.disc.onnected r from *the resistance l. and 'another conductor"similar thereto may beisimi'larlyplacednn the circuit 46. lhe

switch? 23 isthen:-*closed :toenergize the coil 2B which forces; the:.contactor ll into engagement H lWitha-the: contacts I 3- l 9, theswitch 23' opened,

=and:another test may be; conducted Without-loss of-time.

Thai above described devicei gives an operator ==thereof firee control.:as :t0 the opening of the;,; .35

high potential icircuit AB,- but indicates clearly :theperiod:whichian'insulating cover free from defects should hetestedandwhether-such a cover not iound defective: is :actually tested themini- "mum testrperi'od; Anypinoentive to speed up production attheiaex'pense ofcincomplete tests by -shorteni-ng' the test periods iseliminated by the device,describedhereinabove because, if a cover--under test is, not found to be defective, and if "the switchttt hasbeen opened before the-expira-,:;- -tion of the minimum test period-butafter the =contactor t28 and the contact 132 have been disengaged, thetesting circuit 40 cannot be energized bythe reclosingof the switchedbefore the timer-65 completeszits cycle and is reset; But .50 if a coverunder test: is "defective; the entire device is'imm'ediatelydeenergized'and' another testing-operation may be started as soon as theconductor having the'defective cover thereon is reiomoved'and'anotherconductor is inserted in the:-

testing circuit.

'. What is claimed is:

1: ,An apparatus for testing an insulating jacket surrounding aconductor, forming part of an electric cable which comprises a testingcircuit energizable to impress a high potential acros such a conductorconnected therein, a low potential control circuit including meansfor-energizing the high potential testing circuit, means forcontrolnuity controlling means to energize the testing circuit andstartan insulation testing operation on the conductor connected therein,means operable With'the continuity controlling means for indicating whenthe testing circuit is energized, and timing means started by themanually controlled means for indicating whena testingoperation hasbeencon-d-ucted on the conductorior a-predeterminedperiod of' time.

v2- iAn apparatusfor electricallytestingian lin- =,sulated .conductorliora :PIBQGtBmIiHGQKPBP-iOdlOf time; which comprises awtestingicircuitzenergizable: to-impress a .hlghpotentialacross aiconduc- ;tor connectedthereacross, means iorsenergizing the: testing circuit, means'forcontrollingitheycontinuityiofthe: energizing means,- 1manu-allyir-controlled means for energizing the. continuity :con-

trolling-means to energize thertesting circuit and startahighs-potential?testingoperationon a conductor @conneeted therein:timing irneans started by: said manually controlled meansfor;indicating the .passageof: a predetermined: period tor time after thestart of said testingoperationcont-acti-ngv means .contro1led by? atheitimer: and ='e1e.ctricallyconnected torthe manually controlled; meansfor preventing the :reenergization of :the-;=conti ,nuity controllingmeans during'rthe timingzzpe- :riod; means; operable by themanually-:controlled 'means for simultaneously indicatingthecene'rgization of the testinggcircuit and the operatiomof "down the?insulation? of a conductor: connected-tin the testing: circuit; :andmeans for resettingsthe "current responsive means to: closetheeenergizing means.

3'; An. apparatus-foraelectrically testingotheiin- Sulationof-aninsulated-conductor; which loomprises actesting circuit energizabletooimpress a "highpotential; across: an insulatedcconcluctomen- --nectedtherein, means for. energizing'the: testing circuit", a zrelayi for:controllingthe: continiiityrof the energizingtmeans, manuallycontrolled means for energizing the relay'rto ":energizel the testingcircuit andzinitiate a high-1potentialiinsuiation testing operation ranthe iinsulated': conductor,

meanscontrolled by said manually. con trolled means for indicating-theenergization and adeenergization of the testing circuit, timing meansstarted by"the"operation of "the manuallydcon- I trolled meansforindicating thewpassagefiofi a predetermined period" of timerafter theinitiation of a't-estingpperation by said manually-z-controlled means,and meansractuated byithe'itiming means and electrically interlockedwithzthezmanually controlled means, for'preventing the reenergizationofsaid relay after any deenergization thereof effected byardeenergization of themanually controlled means prior to therexpiration of the predetermined perioduof time" if a conductor undertest isnot defective. 4'. An apparatusfor' electrically testingtheinsulating jacketof an insulated"conductorylwhich comprises a"testing circuit energizabletorimpress a high potential across such aconductor connected therein, means for energizing the testing circuit,means for controlling the continuity 50f the energizing means, timingmeanss energiza-ble to indicate": theiassage of a-predeterminedeperiodoftime, resilient means ractuatedwbyasaid timing means during-the timingperiod, for; automatically' resetting saidattiming -means;i toii;-itsstarting -position:upbn :deenerg-iza-tion, :thereof, means operable by:said, timing: means rforzzindieating"whenzsaid period of timehaselapsed, means operable with: said continuity lcontrolling means :f012:: indicating father: energizationwioi ithe conductor connected insaid testing circuit, and

means controlled by the timing means for maintaining the operation ofthe timing means independently of the operation of the manuallycontrolled means, whereby if said testing circuit is deenergized duringthe timing period by the deenergization of the manually controlled meansthe resetting means is not efiective to reset the timing means to itsstarting position until the timing means has completed its timingperiod.

5. An apparatus for electrically testing the insulation surrounding aconductor forming part of an electric cable, which comprises a testingcircuit energizable to impress a high potential across such a conductorand its insulating jacket, means for energizing the testing circuit, arelay for controlling the continuity of the energizing means, meansoperable with said relay for indicating the energization thereof,manually controlled means for energizing the relay to energize thetesting circuit and start a high potential testing operation on theinsulated conductor connected therein, timing means started by saidmanually controlled means for indicating the passage of a predeterminedperiod of time after the start of a testing operation, means connectedin series with the energizing means for indicating when the insulatingjacket of the conductor under test breaks down during the high potentialtesting operation thereon, and means controlled by the timing means forpreventing the reenergization of the testing circuit if said testingcircuit is manually deenergized before the expiration of thepredetermined period of time and the conductor under test is notdefective.

6. An apparatus for testing the insulation surrounding the conductor ofan electric cable, which comprises a testing circuit energizable toimpress a high potential across the insulating jacket of a conductorconnected therein, means for energizing the testin circuit, a controlcircuit for controlling the operation of the testing circuit includingmeans for controlling the continuity of the energizing means, manuallycontrolled means for energizing the continuity controlling means toenergize the testing circuit,

means to start a high potential testing operation on the conductorconnected in the testing circuit, timing means started by the manuallycontrolled means for indicating that a testing operation has beenconducted on the conductor for a predetermined period of time, andresilient means actuated by the timing means during a testing operationfor instantaneously resetting the timing means to its starting positionupon the expiration of the testing operation.

7. An apparatus for con-ducting a high potential insulation test on aninsulated conductor forming part of an electric cable for a fixed periodof time, which comprises the combination of a testing circuitenergizable to impress a high potential across the insulating jacket ofa conductor connected therein and having means associated therewith forenergizing the testing circult and a control circuit including means forcontrolling the continuity of the energizing means, manually controlledmeans for selectively operating the continuity controlling means toenergize the testing circuit and initiate a high potential testingoperation on the insulation of a conductor connected therein, timingmeans started upon the actuation of the continuit controlling means forindicating the passage of a, predetermined period of time after thestarting of a testing operation, and means connected in series with theenergizing means and responsive to an increase of current flowingtherein, whereby if the high potential testing operation breaks down adefeet in the insulation of a conductor connected in the testing circuita high current will flow therein causing an increased current flow inthe energizing means and the current responsive relay, which relay willbe actuated thereby and deenergize the energizing means and the timingmeans simultaneously.

8. An apparatus for electrically testing the insulating jacket of aconductor for a fixed period oftime, which comprises a stepuptransformer, a testing circuit including the secondary winding of thetransformer energizable to impress a high potential across theinsulating jacket of a conductor connected therein, a power supply, arelay for connecting the primary winding of the transformer to the powersupply and energize the testing circuit, a second relay for energizingthe first mentioned relay, radiant means for indicating when the firstmentioned relay is energized, a third relay for controlling theoperation of the second relay, a manually operable switch for energizingor deenergizing the'third relay to energize or deenergize the testingcircuit at will, a

fourth relay energized by the third relay, timing means energized by thefourth relay, means provided on the timing means for maintaining saidfourth relay in an energized position, means provided on said fourthrelay for maintaining the timer in continuous operation for apredetermined period of time after an actuation of the manually operableswitch, said timing means also being provided with contacting meanselectrically connected with the second relay for preventing thereenergization of the first and second relays prior to the expiration ofthe predetermined period of time if the insulating jacket of theconductor under test is not defective, a fifth relay having its closingcoil connected in series with the primary winding of said transformerand responsive to an increase of current flowing therein fordeenergizing the above mentioned relays only if the insulating jacket ofa conductor being tested is defective, and resilient means actuated bythe timing means for permitting the reenergization of the first andsecond relays before the expiration of the predetermined period of timeif the fifth relay is actuated by the presence of a defective insulatingjacket on the conductor connected in the testing circuit.

- CLAY E. LEWIS.

REFERENCES CITED The following references are of record in the file ofthis patent:

